The ramblings of an electronic amateur

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Anthrophex: Part 2 – The build

I guess now would be a good time to disclaim my machining abilities. I can safely say that I’d make a shocking machinist but I guess its the effort that counts right? Regardless, with the arrival of parts, the build could begin!

The leg and hip hinges

As all of the aluminium was pre cut (literally a god send), all I really had to do was drilling and manufacture. I had chosen aluminium that was thick enough to be tapped which eliminated the requirement of nuts at the expense of extra effort tapping all of the aluminium.

Laying out all the aluminium and hinges in my tip of a room. Dimensions hasn’t been measured yet.

Drilling and tapping the leg and hip pieces

The full leg design with hinges

For most of the hinges, I only tapped two of the three holes to save on bolts.

Making up the body!

With two holes on each crossbar and tapped holes on the long pieces, the frame seemed strong enough without supporting bars on the underside. For this reason, they weren’t added in. I still have the aluminium so if they’re needed at a later date, I can always add them on!

Adding all of the legs and attaching them to the body

It was by this point that I really got a view on how large it was going to be… and damn was it bulky.

Testing under free standing mode

While the legs won’t be anywhere near the angles in the image above, it was really great to see that it could support its own weight!

At this point in the build. I hadn’t actually got the actuators yet so a longer wait was required for those. Once they had arrived however, I was able to fully build the legs and joints.

One actuator! I actually didn’t get scammed…

Laying out a leg with one of the actuators

All actuator holes drilled!

It turned out that there was a minor issue with the actuator brackets – not all of the holes had been drilled to the same diameter so my M5 bolts didn’t fit into all the holes, this meant redrilling all of the bracket holes (4×12 = 48 ugh)!

All done!

A full leg can now finally be assembled!

Testing out one of the actuated legs in a bench vice. This was tested with my 12v PSU.

By this point, real assembly could take place back at home so my friend was kind enough to pick up the parts to save me cycling with them all (yes, I actually cycled to the hackspace with alllllllll this aluminium).

Voila! The current final product.

And here we are! We have the human hexapod standing freely alone in my room! It was at this point that excitement got the best of me and I gave it a try.

The first test of course was seeing if it could support all of my weight so I slowly sat on it and lo and behold, it supported all of my weight without collapsing in on itself!

The next step was to set it into the tripod gait and see if it could still support my weight. Sadly, here was where the issues started. There is a running joke between me and my friend that if possible, I would use hinges for absolutely everything. It might be a joke but its true! If there is anything that could use a hinge, I will try my hardest to get a hinge on it. Most the time it has worked fine and left me no issues… Apart from this time. The hinges were a major point of weakness and once I sat on it, they started to distort pretty drastically. This distortion was enough to bend one of the hinges so far out of shape, that the hexapod couldn’t even stand straight anymore.

Disaster! Hinge distortion…

I probably should’ve paid way more attention to these hinges, it is now obvious that 2mm thick 75mm steel hinges just aren’t cut out for this job. I’ve got some heavier duty hinges on the way now which can hopefully support my full weight without distortion and therefore allow me to continue with the project!

I’m now at home (i.e. not Nottingham) so I won’t be building for a while as I need to wait for parts to arrive anyway. Keep tuned for more updates!